The invention relates to a safety device for a high-voltage system and a method for safeguarding a high-voltage system, in particular for a high-voltage battery of an electrical drive system.
It appears that electronic systems which combine new energy storing technologies with electrical drive technology will increasingly be used in the future in stationary applications, such as, for example, wind turbines or solar plants, as well as in motor vehicles, such as hybrid or electric vehicles.
Electrical drive systems, for example, in electrically driven vehicles such as hybrid vehicles, electric cars, fuel cell vehicles or vehicles with Range Extender have components for energy storage and energy conversion which operate with electrical high voltages. Electrical high voltages are in this case voltages of more than 60 volts which can be potentially live threatening for humans. For that reason, an electrical insulation of said high-voltage components with respect to the vehicle, the passengers and possibly further persons involved with the motor vehicle is necessary.
It must be ensured for the inspection, servicing and repair of high-voltage components that firstly unauthorized persons are prevented access to the high-voltage components and secondly that no danger can occur to persons working on the high-voltage components. The first boundary condition is met for the most part by so-called “service disconnect” devices, with the aid of which access to the high-voltage components is only possible with the use of a special tool. The American patent publications US 2007/0235313 A1 and US 2008/0297303 A1 disclose examples for such service disconnect devices.
Additional measures are required in order to furthermore ensure that high voltage is no longer being applied to the high-voltage components when said components are being externally accessed. In the case of known measures, such as, for example, those disclosed in the American patent publications U.S. Pat. No. 7,402,068 B1, U.S. Pat. No. 7,530,850 B2 or U.S. Pat. No. 7,084,361 B1, access to the high-voltage components is made more difficult by means of suitable mechanical measures in order to provide a sufficient amount of time after a deactivation of the high-voltage system for the high-voltage components to be discharged. In other solutions, such as, for example, that described in the American patent publication U.S. Pat. No. 7,679,211 B2, a possibly present high voltage is redirected across a resistor in the service disconnect device.
The American patent publication US 2004/0017643 A1 further discloses a locking system for a cabinet comprising components for carrying electrical current, wherein the cabinet is only then unlocked if the voltage at the components lies below a threshold value.